This thesis consists of a comprehensive review of bidirectional charging technology, with focus on understanding the technical requirements and the challenges that has to be overcome to standardize this innovation. The thesis is based on three main objectives or goals that is needed to be able to answer the main review question which is: What does it take to standardize, develop and make bidirectional charging a reliable technology? The first objective is to review and explain how the technical bidirectional charging ecosystem works. It starts by explaining in detail how bidirectional charging works and looking closely at how the charging station, electric vehicle (EV), and the power grid connect and work together. The second objective consist of exploring the challenges and the benefits of bidirectional charging. The main challenges explored are social challenges, regulatory challenges, technical challenges and battery degradation. The main benefits explored in this thesis are: offloading the power grid, environmentally friendlier benefits, economic benefits and better management of renewable home systems. The third and final objective in this thesis covers a surveying of existing bidirectional charging products and solutions like Fords F-150 lightning V2G technology and CHAdeMO 2.0. Explaining what they are and their potential success in the European market. The thesis concludes by addressing and discussing the central researched question, which indicates that bidirectional charging is still a young technology that needs to overcome many challenges and improve in some areas before it can be widely used by consumers in a safe and effective way. The results show that the speed and success of the development of this technology depend on how well the actors and stakeholders cooperate with each other and how fast the regulations and standards evolve. EU and Swedish regulations need to keep developing standards for better interoperability. This will help create a legislation for independent market players and key stakeholders, making it easier for them to interact and make compatible products. Therefore, the research done in this thesis suggests that in order to standardize bidirectional charging, different actors, stakeholders and regulatory organizations need to work together better in the future to make V2X safe, standardized and interoperable. There are very few V2G solutions available for customers today, but with the cooperation of key actors, new ISO standards and EV manufacturers making more compatible cars, this technology has the potential to become more accessible in the upcoming years.

In this study, onboard chargers for EVs are investigated and a design of bi-directional onboard chargers is proposed and simulated. The goal of the charger is to be built in the future to be used in the test setup at Uppsala University. The charger consists of two stages: a power factor correction (PFC) converter, which converts AC voltages and currents from the grid side to DC while maintaining a unity power factor, and a bi-directional buck-boost converter, which regulates the charging and discharging current of the battery. The model was built using MATLAB/SIMULINK and the d-q synchronous reference frame was utilized to implement the current controller of the PFC converter, while the bi-directional buck-boost current controller was constructed using DC pulse width modulation. The Proportional and Integral gains were tuned using the MATLAB single input and single output tool (sisotool). The converter's topologies, structure, and corresponding mathematical model were investigated, and the charger was simulated and tested for charging and discharging modes. The battery voltage, current, and state of charge were monitored during all modes of operation to evaluate the performance of the buck-boost controller, and the functionality of the PFC controller and filter was tested by measuring the currents and voltages on the AC side. The charging and discharging efficiencies were mapped under various battery voltages and current sets to determine the performance of the charger under different operating conditions. The charger demonstrated excellent performance during charging and discharging modes and recommendations for future work to improve the efficiency and performance of bi-directional charging systems were provided.

As the world undertakes global climate goals to lower the emissions of greenhouse gases, more renewable energy sources are introduced in the electrical energy system, and fossil fuel driven combustion engines aims to be replaced by electric vehicles. New problems connected to the transition such as voltage fluctuations, production and consumption mismatch and high peak loads, requires new solutions. Such a solution could be to use smart charging algorithms and bidirectional charging for electrical vehicles in order to avoid further increased power demand during peak demand hours and to make the electric vehicle a resource more than solely as a mode of transportation. Such resource could be a battery storage for the home by using a vehicle to home strategy and for the electrical grid by using a vehicle to grid strategy. These strategies demand certain technology with only a few options available on the market today, but with a lot of recent and ongoing research on the way. In this thesis a smart charging algorithm is developed which aims to lower a households electricity cost by optimizing charging and discharging of an electric vehicle. The charging may come from the grid or the household’s photovoltaic system and the discharging may go to the house home appliances or back to the grid, utilizing vehicle to home and vehicle to grid strategies. The algorithm was tested in MATLAB for five different scenarios showcasing these possibilities and simulated in combination with five different user profiles. The results show that the charging peaks are moved to an area of less consumption and verify that the electricity costs can be lowered on daily and yearly basis.